Answer:
[tex]\large \boxed{12}[/tex]
Step-by-step explanation:
We can apply Pythagoras' Theorem.
[tex]\begin{array}{rcc}a^{2} & = & b^{2} + c^{2}\\13^{2}& = & 5^{2} + c^{2}\\169& = & 25 + c^{2}\\c^{2}& = & 144\\c & = & \sqrt{144}\\& = & \mathbf{12}\\\end{array}\\\text{The other leg of the triangle is $\large \boxed{\mathbf{12}}$}[/tex]